Concrete masonry blocks are made in automated production plants and typically are uniform in appearance. In certain applications, this is not an undesirable characteristic, but in other applications, it is a drawback where there is a demand for other aesthetic or face styles used to construct walls or other structures.
One way to make concrete masonry blocks less uniform and more natural appearing is to use a splitting process to create a rock face, or a split face, on the block. In this process, as it is commonly practiced, a large concrete work piece which has been adequately cured after molding is split to form two blocks. The resulting faces of the resulting two blocks along the plane of splitting are textured and irregular, so as to appear as more naturally occurring rock faces. This process of splitting a work piece into two masonry blocks to create a rock-like appearance on the exposed faces of the blocks is shown in U.S. Pat. No. 1,534,353, incorporated herein by reference, which discloses the manual splitting of blocks using a hammer and chisel.
Automated equipment to split blocks is well-known and can include various types of powered splitting blades. A splitting blade in this application is typically a substantial steel plate that is tapered to a relatively narrow knife edge. The blades are typically arranged so that the knife edges will engage the top and bottom and side surfaces of the work piece.
These machines are useful for the high speed processing of blocks. They produce a split face finish on the blocks. No two faces resulting from this process are identical, so the blocks are more natural in appearance than standard, non-split blocks.
Other ways of treating masonry blocks in a manner to result in a more decorative, and less machine-generated look, is by putting the block through a burnishing process. In a burnishing process, the target surface is subject to multiple grinders, in which a belt sander will grind, polish, and expose aggregate in the treated face of the block. The resulting block face has a very formal, polished appearance, with visible aggregate. However, in some application, this appearance is more formal and uniform than is desired. In contrast, a block with a resulting split face has the appearance of being very informal. A split face also can have sharp protrusions extending from the exposed face, and if used in an environment with close contact to people, it can catch clothing. There is a need for a masonry block that is convenient to manufacture that is does not have the appearance of the highly formal surface of burnishing and which does not have the drawbacks of a split face.